The present invention relates to a method for forming a pressure seal for the fiber product feed in and take out parts provided in a high pressure steamer.
Heretofore, a method for forming pressure seal in a high pressure steamer has had such shortcomings that steam being under pressure into the vessel body of a high pressure steamer is heated to have high temperature during operation making it difficult to retain the atmosphere (pressure, temperature, etc.) of the steam at a state suitable for processing fiber products, further the temperature within vessel body rises to the high temperature of the steam causing thermal expansion to take place at each sealing member of the seal device of the steamer, moreover, as the coefficient of thermal expansion of each of the seal members is different each sealing member is placed in pressure contact with the other by great pressure with the sealing gas under high pressure within the vessel chamber affecting strain deformation, causing pressure seal leakage and thus lowering the safety of operation, furthermore, the durable life of the seal apparatus is shortened, and the time, trouble and expenses required for maintenance of the apparatus increase, also adversely affecting operating efficiency.
Pressure seal apparatus for the fiber product feed in and take out parts of a high pressure steamer vessel body used in a conventional pressure sealing method ordinarily has such method as providing a roll seal mechanism consisting of such sealing members as a pair of left and right seal rolls rotating in contact with each other, a seal block installed at the fiber feed in and take out openings of vessel body, and intermediate rolls intervening between the seal rolls and the seal block, etc.
However, in a sealing apparatus having said set-up, the temperature within steamer vessel body rises during operation as mentioned above and each sealing member of said sealing apparatus directly receives the effect of high temperature which causes thermal expansion, resulting in strain deformation at each sealing member in contact with the other because of their coefficients of thermal expansion being different and causing pressure seal leakage, thereby it becomes difficult to retain the atmosphere of steam pressure introduced into vessel body at such a constant state as is suited for processing the fiber products, and the elastic substance for seal rolls becomes fragile because of defects of a mechanism to adjust change in the atmosphere, etc., thereby shortening the durability life of the seal apparatus.
Furthermore, in a seal apparatus having above mentioned mechanism the pressure contact points between a pair of left and right seal rolls and the sealing member which pressure contacts with circumferential surface of the rolls, that is, the pressure sealing points in the circumferential direction of said rolls are such that the nip planes formed by the seal rolls form almost right angle against the axial centers of the rolls, therefore the seal roll circumferential plane receiving the pressure within the vessel is great and the pressure giving force over seal roll required for formation of nip plane needs to be comparatively large. Therefore, the driving force for such seal rolls becomes large, and further the effect on fiber products passing through nip plane also increases.
The object of the present invention is to prevent various shortcomings generated in this conventional method and by providing a pressure seal method employing air balance in a high pressure steamer embody said method, and realized a method and an apparatus in which pressure seal operation is done safely and surely, and the roll seal mechanism of seal apparatus used will not be directly affected by high temperature thereby providing any fear of deformation and securing a long durable life.